Best JSON Parsers, Viewers and Formatters

Open a raw API response in a browser tab and you get one line, forty thousand characters long, no line breaks. Somewhere in there is the field you need. That is the whole problem a JSON viewer solves: indentation, syntax colours, collapsible nodes, type hints, and a validator that names the comma you forgot.

Below are the tools worth using as of August 2026, roughly in the order you reach for them. Versions, prices and size limits are current as of this update, which matters more here than it should: two tools that older round-ups still call free are not, and one of them is usually recommended for exactly the job its free tier no longer does.

The short answer

1. JSON Editor Online for anything you need to edit, compare, repair or query in a browser.
2. JSON Crack when it is the structure, not the values, that has you confused.
3. JSON Formatter by Callum Locke as the extension to put on Chrome.
4. JsonTools as the Notepad++ plugin that replaces the two older ones.
5. jq 1.8.2 on the command line. Update yours; 1.8.2 is a security release.
6. Miller (mlr) for JSON Lines and files bigger than your RAM.
7. DevToys for anything that must not leave your machine.

The rest of this page is why, plus the alternatives worth knowing.

Before you paste anything into a website

In November 2025 the security firm watchTowr Labs reported that two popular online formatters, jsonformatter.org and codebeautify.org, had been exposing user-submitted content through their "save and share" features. Around 80,000 files, roughly 5 GB, containing Active Directory credentials, database connection strings, cloud API keys, private keys and internal bank data. Nothing was breached in the usual sense. People pasted secrets, clicked save, and the resulting links were public with guessable IDs.

The lesson is narrower and more useful than "never use online tools". Formatting is normally harmless, and several tools below never send your data anywhere. The dangerous feature is persistence: any button labelled save, share link, or cloud document means a copy of your payload now sits on someone else's disk behind a URL you do not control.

Three rules cover nearly every case. Pasting into a formatter that works in the browser is fine. Clicking "share link" is publishing to the open web, so treat it that way. And customer records, tokens and internal hostnames go into local tools only. Where a tool states clearly which side it falls on, it is noted below.

What your browser already does

Half the extensions people install solve a problem their browser fixed years ago.

Firefox has had a built-in viewer on by default since version 53, April 2017. (It landed in Firefox 44 in 2016, but only in Developer Edition and Nightly.) Collapsible tree, filter box, separate tabs for raw data and headers. For day-to-day API poking that is enough.

Edge ships its own viewer, on by default since February 2023, for both JSON URLs and local .json files. This is the detail that trips people up: Chromium browsers are not all alike here.

Chrome still has nothing. An application/json URL renders as unformatted plain text in the viewport. It does not download the file and it does not pretty-print it. DevTools is a different story, since the Network panel's Response and Preview tabs have pretty-printed JSON automatically since Chrome 110, but that only helps when DevTools is already open on the request. For a URL in the address bar you need an extension.

Safari has no documented built-in viewer, and the size of the JSON-formatter market in the App Store suggests the gap is real.

Online viewers and formatters

JSON Editor Online

jsoneditoronline.org · source: svelte-jsoneditor

The tool most "JSON editor" clones are copied from, and the one to open first. Three modes side by side (code, tree, table), and it is a real editor: change values, repair a broken document, save your work. It validates against a JSON Schema using Ajv, compares two documents on a data level so whitespace and key order do not create noise, and queries with four languages: JSON Query (now the default), JMESPath, JSONPath, and plain JavaScript with Lodash.

The number older reviews quote is 512 MB, and it is right for what the editor will open from disk. The number they miss is 1 MB, the cap on any document saved to the cloud, on every tier including the paid ones. Free shows ads and includes tracking; Premium is $9 a quarter without either, Pro $18 a quarter with 1 GB of storage. Built by Jos de Jong, library at v3.12.0 as of March 2026. The older jsoneditor library is still maintained and is not a drop-in equivalent, so projects on it are not stranded.

JSON Viewer (stack.hu)

jsonviewer.stack.hu

Online since 2008 and still getting work: the site logs a performance fix in June 2026. Paste, switch between raw text and a collapsible tree, minify or beautify. It gained a "Load JSON data" button for file import in April 2025, the one thing it lacked for years. The site says it stores nothing server-side and runs no database at all, and it is served over HTTPS.

Two things older write-ups get wrong: it is ad-supported, and $19 one-time removes the ads and speeds up loading. "No-frills" describes a version from a decade ago.

JSONLint

jsonlint.com · source: circlecell/jsonlint

The best-known dedicated validator, now maintained by CircleCell. Paste, validate, get the syntax error pinned to a line. It has grown a formatter, a minifier and a repair function, but the validator is still the reason to go. Relevant to the section above: its privacy policy states validation runs entirely client-side and JSON content is never sent to its servers or logged. Google Analytics and BuySellAds are on the page, which is a separate question from where your payload goes.

JSON Formatter & Validator (Curious Concept)

jsonformatter.curiousconcept.com

Running since 2007, and useful for one specific thing: choosing which specification to validate against. RFC 8259 by default, with ECMA-404, RFC 7159 and RFC 4627 also on offer, plus skip-validation. Indentation goes down to compact. If you are arguing about whether a top-level scalar is legal JSON, this settles it.

One caveat. Its own wording, that data "is merely processed and returned directly to you", reads like a server round trip, and the site never claims in-browser processing. Use it for spec questions, not for payloads you care about.

jsonl.co

jsonl.co is new, and it fills a real gap. JSON Lines (one object per line, no wrapping array) is what comes out of log exports, LLM fine-tuning sets and most large scrape dumps, and it breaks classic viewers because the file is not a single JSON document. This one handles 1 GB and up in the browser and converts JSONL to and from CSV and JSON.

Dadroit V Web

dadroit.com is a free browser viewer for large files, from the team behind the desktop app. Tree view, keyword and regex search, loading from a URL with authentication, exporting a filtered subset. The file stays on your machine.

One to skip: json.parser.online.fr

Older round-ups list this French single-page parser, earlier versions of this guide included. In August 2026 it runs on Free.fr consumer hosting, and its own privacy policy describes a server round trip: uploaded data is "read and injected into the page you requested then destroyed". It sets cookies and logs IP and browser data too. Everything it does is available elsewhere from a tool that never touches your data.

Visual and graph-based explorers

A newer class of tool draws JSON as an interactive diagram instead of an indented tree. Not a gimmick when a document is deeply nested and you are trying to work out its shape rather than read its values.

JSON Crack

jsoncrack.com · source: AykutSarac/jsoncrack.com

Free, Apache-2.0, 44,000 GitHub stars, and it draws your data as a node graph or a tree while you type. It reads YAML, CSV and XML, converts between formats, validates, runs jq and JSONPath queries, generates types (TypeScript, Go, Kotlin, Rust, JSON Schema) and exports the diagram as PNG, JPEG or SVG. Everything happens in your browser. There is an official VS Code extension with around 755,000 installs and a much smaller official Chrome extension.

Worth correcting a story that circulates about this project: JSON Crack did not go freemium. It went the other way. It used to have a premium plan, and those features moved out to a separate paid product, ToDiagram, by the same author. The site has no paywall and no byte limit. The 300 KB figure in its FAQ is an estimate of where the graph starts to feel slow on typical hardware, not a billing threshold.

JSON Hero

jsonhero.io · source: triggerdotdev/jsonhero-web

From the Trigger.dev team, and still the nicest thing to hand someone who has never seen the API you are describing. Switchable column, tree and editor layouts, and it recognises what values are: images, colours, dates and URLs get previewed inline. Apache-2.0 and self-hostable. The site is live and the repo is not archived, but the last push was November 2025, so treat it as stable rather than actively developed.

Browser extensions

On Firefox and Edge you may not need one. On Chrome you do.

JSON Formatter by Callum Locke is the default recommendation, mostly on the strength of being looked after: two million users, 4.3 out of 5 from over two thousand ratings, updated May 2026.

JSONView by Ben Hollis (source) is the one most people mean when they say "the JSON extension". It formats application/json in place with highlighting and collapsible arrays, and falls back to raw text when the document is malformed, which is more useful than it sounds. MIT licensed, and version 3.0.0 made it Manifest V3 compatible, so it survived Chrome's MV2 shutdown. Current release 3.2.0, May 2025: 100,000 Chrome users at 3.8, 16,000 on Firefox at 4.1. Maintained, but slowly. No Safari build; the author has pointed at Apple's $100 a year developer fee. Install it under Ben Hollis's name, not from a fork.

JsonDiscovery (source) is the power-user option, built on Discovery.js. Interactive tree, queries in the Jora language, shareable custom reports, works offline and on local files, and it derives a TypeScript-like signature of your data, which is genuinely handy when you need to know what shape an endpoint returns rather than what it happened to return this time. Chrome is on v1.17.0 from September 2025; the Firefox build lags at v1.14.1 from May 2024.

JSON Viewer Pro, 300,000 users and 4.6 out of 5, is the third option if the ergonomics of the other two annoy you.

Firefox tip that still applies in 2026: several of these render nothing until you disable the native viewer. Open about:config, find devtools.jsonview.enabled, set it to false.

Notepad++ plugins

Install through Plugins → Plugins Admin, which replaced the third-party Plugin Manager in Notepad++ 7.6 (November 2018). Plugin Manager's own README now tells you to stop using it.

JsonTools

Source: molsonkiko/JsonToolsNppPlugin · in Plugins Admin as "JSON Tools"

This is the one to install, and it is missing from nearly every round-up on the subject, which is why it goes first here. Version 8.5 shipped in March 2026, the 59th release.

What it does that the older plugins do not: a query language called RemesPath; JSON Schema validation, including automatic validation of a file based on its name; schema generation from a document and random document generation from a schema; a linter that parses and repairs files with real syntax errors, missing commas and unterminated strings included, rather than refusing to open them; JSON to and from CSV; JSON Lines support; a regex search form that does find-and-replace with arithmetic on the matches; array sorting; a dockable tree with search, click-to-navigate and path-to-cursor; JSON5 and Python-style comments; and a form for pulling JSON straight from an API or a local file into the editor.

One known issue as of 8.5: on ANSI-encoded files containing non-ASCII characters, the position-dependent features are still unreliable. Save as UTF-8 and it behaves.

JSON Viewer

Source: NPP-JSONViewer/JSON-Viewer

The long-standing tree-panel plugin by Kapil Ratnani and Rajendra Singh. Note that the repo moved to its own organisation; the old kapilratnani/ path most articles still link is stale.

It does more than the tree it is known for: formatting with configurable indentation and line endings, sorting keys, validation with the error position highlighted, copying a node's value or path, and optional tolerance for trailing commas, comments and NaN/Infinity. Selecting a node highlights the matching text in the editor, which is what earns it a place in a large file. Latest release 2.2.0.0, May 2024; the repo still takes dependency bumps but feature work has been still for about two years. If JsonTools is more than you want, this is the quieter choice.

JSTool: read this before installing

sunjw.us/jstool/npp · source: sunjw/jstoolnpp

JSTool is the plugin formerly called JSMinNpp, and for years it was the right answer: format and minify JavaScript and JSON with Ctrl+Alt+M, sort keys alphabetically, browse a built-in tree with Ctrl+Alt+J, and by the author's account handle files past 10 MB without complaint.

The Notepad++ edition is now end of life. The author's page states there will be no updates after version 25.11.16, released 16 November 2025, and development continues on the VS Code edition only. Plugins Admin still offers 25.11.16 and it still runs, but you would be installing a plugin that will never be patched again. JsonTools covers both the formatting and the key sorting.

Command line

jq

jqlang.org · source: jqlang/jq

Still the default. It pretty-prints, filters, reshapes and queries JSON in a terse language that repays the afternoon it takes to learn, and it exists on every platform you are likely to use.

Update yours. The current release is 1.8.2, 20 June 2026, and it is a security release fixing sixteen CVEs, among them buffer and stack overflows and a hash-collision denial of service. That matters directly if you pipe untrusted JSON, scraped pages or webhook payloads, through jq inside an automated job. For the record, the project moved from stedolan/jq to the jqlang organisation after a five-year silence and has been maintained again since 1.7.

Miller (mlr)

Source: johnkerl/miller

The tool to reach for when the file does not fit in memory. Miller streams, holding one record at a time, so multi-gigabyte files and JSON Lines are routine rather than an occasion. It reads and writes CSV and TSV natively, which turns "send me this as a spreadsheet" from a script into a flag. Version 6.18.1, April 2026.

fx

Source: antonmedv/fx

An interactive terminal viewer: arrow keys to walk the tree, collapse and expand, search, JavaScript expressions when you want to filter without leaving the pager. Input can be streamed, so a large NDJSON file is fine. jless was purpose-built for the same job and is nicer in places, but it has had no commits since June 2024, so fx is the recommendation now.

gron

Source: tomnomnom/gron

Flattens JSON into one path = value; line per leaf so that grep works on it, then reverses the transformation with gron -u. This is the answer to "I saw that string somewhere in this 3,000-line response, where does it actually live". Last release 0.7.1 in 2022, which reads as finished rather than abandoned.

jsonrepair

Source: josdejong/jsonrepair

A library and CLI that fixes JSON that is nearly JSON: trailing commas, unquoted keys, single and curly quotes, // and /* */ comments, missing brackets, truncated documents, Python's None/True/False, JSONP wrappers, fenced code blocks, and NDJSON that should have been an array. It has a streaming mode for large input, powers JSON Editor Online's repair button, and belongs in front of any parser that has to eat scraped or model-generated JSON.

Also worth knowing

jaq (Rust reimplementation of jq, faster, also reads YAML, TOML and CBOR), gojq (pure Go, arbitrary-precision integers), yq (jq syntax over YAML, XML, CSV and TOML, with explicit NDJSON support), dasel (query and modify across eight formats), jd (structural diff and patch, RFC 6902 and RFC 7386), jnv (builds jq filters interactively while you watch the result), and jc (converts the output of 150-plus Unix commands into JSON, which sounds strange until the first time it saves you a regex).

Desktop applications

Dadroit JSON Viewer

dadroit.com

Built for very large files, and by the vendor's numbers it is fast: around 2 GB/s file reads, 130 million objects a second parsed, roughly 1 GB of RAM per gigabyte of file. JSON Lines support, regex search, merging several files, export to CSV and XML. Windows, macOS and Linux; version 3.3.0, July 2025.

Now the part most articles, this one's previous version included, get wrong. Dadroit is not free. The free tier is non-commercial and caps files at 50 MB, which excludes precisely the scenario people recommend it for. Standard is $98 a year for files up to 2 GB, Advanced $198 a year for up to 1 TB plus multi-file union. Fair enough for a tool that saves you an afternoon, but it should not be presented as a free download. And every performance figure in circulation traces back to Dadroit's own marketing; there is no independent benchmark worth citing.

DevToys

devtoys.app

An offline toolbox of about thirty developer utilities, including a JSON formatter, bidirectional JSON-to-YAML conversion and validators. Version 2.x runs on Windows, macOS and Linux; cross-platform arrived with 2.0 and the follow-up 2.0.x releases fixed the macOS and Linux rough edges, so it is real rather than announced. Latest release 2.0.9.0, January 2025, with commits continuing into 2026. If your rule is that nothing sensitive goes into a browser tab, this is what makes the rule practical.

The editor you already have

VS Code validates JSON against schemas out of the box through json.schemas and SchemaStore, with IntelliSense on known schema files, formatting and folding. Both JSON Crack and JSTool ship VS Code extensions. For JSON Lines, quick-jsonl-viewer previews large .jsonl files without loading them whole.

JSON when you are scraping

Most JSON in a scraping project does not arrive as a clean API response. Four situations, and what actually helps.

The data is in the page, not in an API. Server-rendered React and Next.js sites embed their state in a <script id="__NEXT_DATA__" type="application/json"> tag; Nuxt puts it in window.__NUXT__; almost every ecommerce product page carries application/ld+json blocks with product, price, availability and review data, because search engines ask for it. Pull the script contents out, drop them into a tree viewer, and find your fields before writing a single selector. Faster than reading rendered HTML, and the result survives redesigns that would break CSS paths.

What you extracted is not valid JSON. Inline state is often a JavaScript object literal rather than JSON: unquoted keys, single quotes, trailing commas, undefined, sometimes a new Date(...) call. json.loads refuses all of it. jsonrepair handles most of these automatically and streams the large cases; JsonTools and JSON Editor Online do the same interactively while you are still working out the shape.

The dump is JSON Lines and it is enormous. Scraper output is usually one object per line, which no browser tool will open. mlr --ijson --ojson streams it and jq -c works line by line; jq's --stream mode handles the other case, a single huge document with no line breaks to split on. For a quick look at a few hundred megabytes, jsonl.co or fx.

The client wants a spreadsheet. mlr --ijson --ocsv cat scraped.jsonl for flat records. Miller flattens nested objects on its own, which is usually what you want and occasionally exactly what you do not; when you need control over which fields appear and in what order, jq -r with @csv is worth the extra typing.

One more, and it has consequences: scraped data very often contains personal data. Pasting a sample into an online formatter for a quick look is a transfer to a third party, and if that tool has a save-and-share button, see the top of this page for how that ends. Names, emails, addresses, anything a client would call theirs: DevToys, jq, or your editor. Not a tab.

Feature comparison

How to choose

• Quick paste and read. Your browser, if it is Firefox or Edge. Otherwise JSON Viewer (stack.hu) or the JSON Formatter extension.
• Edit, compare, repair or query in a browser. JSON Editor Online.
• Work out the shape of something tangled. JSON Crack for the graph, JSON Hero for a readable walkthrough.
• Inspect API responses as you browse. JSON Formatter on Chrome, JsonDiscovery if you want queries and type signatures.
• Working in Notepad++. JsonTools. Not JSTool, which is end of life.
• Automating or scripting. jq, with jsonrepair in front of anything untrusted.
• Files bigger than memory, or JSON Lines. Miller on the command line, Dadroit on the desktop if you will pay for it.
• Data that must not leave the machine. DevToys, or the tools already on it.

Dead ends and renames

• jamiew/jsonview-chrome was archived in November 2018 and is unrelated to the JSONView in the stores. Install Ben Hollis's cross-browser version.
• JSMinNpp became JSTool, and the Notepad++ edition is now end of life. VS Code only from here.
• kapilratnani/JSON-Viewer moved to the NPP-JSONViewer organisation.
• jless has had no commits since June 2024. Lovely tool, unmaintained; use fx.
• json.parser.online.fr is legacy hosting with a server round trip.
• Image-preview viewers. Some first-generation tools rendered image URLs found inside string fields as thumbnails. It was never standardised and those tools are mostly gone. No current viewer depends on it.
• jsonformatter.org and codebeautify.org save-and-share links. See the top of this page.

Changelog

August 2026. Added JsonTools, Miller, fx, gron, jsonl.co, Dadroit V Web, JSON Formatter and JSON Viewer Pro. Corrected Dadroit's pricing, which is not free. Flagged JSTool's Notepad++ edition as end of life and JSON Viewer's move to a new repository. Corrected the widespread claim that JSON Crack went freemium. Added Edge's built-in viewer and clarified Chrome's actual behaviour. Updated jq to 1.8.2 and noted the CVE fixes. Dropped json.parser.online.fr from the recommendations. Added the sections on the November 2025 formatter leak and on JSON in scraping work.